Theophilos (Greek: Θεόφιλος; sometimes Latinized or Anglicized as Theophilus) was the Byzantine Emperor from 829 until his death in 842. He was the second emperor of the Amorian dynasty and the last emperor to support iconoclasm. Theophilos personally led the armies in his lifelong war against the Arabs, beginning in 831.

Theophilos was the son of the Byzantine Emperor Michael II and his wife Thekla, and the godson of Emperor Leo V the Armenian. Michael II crowned Theophilos co-emperor in 822, shortly after his own accession. Unlike his father, Theophilos received an extensive education from John Hylilas, the grammarian, and was a great admirer of music and art. On 2 October 829, Theophilos succeeded his father as sole emperor.

Michael was the youngest child of the emperor Theophilos and his empress Theodora. Already crowned co-ruler by his father in his infancy in 840, Michael had just turned two years old when his father died and Michael succeeded him as sole emperor on January 20, 842.